Some transmitters that utilized high-power vacuum tubes are susceptible to damage by transient conditions within the devices and/or temporary anomalies within the tubes themselves. Should any of the conditions occur, and power continues to be provided to the tubes there is a significant risk of damaging the tubes beyond repair. Previously, to alleviate these concerns, a “crowbar” circuit was implemented within the transmitter using a mercury ignitron tube and multiple sensing circuits within the transmitter were configured to detect problematic conditions developing within the transmitter and to send an initiate signal to the ignitron. The ignitron would then provide a direct short-circuit of the power supply to ground, depriving the tubes of power and also draining stored energy within the transmitter away from the tubes. This short circuit would remain in effect until the protective relays in the power system detected the short circuit and tripped the associated circuit breaker. The unfortunate side-effect of this operation is that it places incredible electromagnetic stresses on the power supply equipment and draws substantial energy from the power system. This also causes a significant drop in system voltage until the short circuit is removed. There exists a need for an improved protective circuit.